The present invention relates to a contact arrangement with an electrical plug connection, in particular with a plug connection between an electrical device and an exchangeable storage battery for current supply of the electrical device.
The invention also deals with an electrical device which is provided with an exchangeable storage battery for current supply and such a contact arrangement.
Contact arrangements of the above mentioned general type are used for network-independent electrical tools, to provide an electrical connection between the storage battery during the use of a charge storage battery in an electrical tool on the one hand, and to provide a current circuit of an electrical drive motor of the electric tool. The storage battery for this purpose has two contact tongs which are arranged on one plug part and are inserted in a receiving part of the electric tool between an oppositely located pair of tulip- or contact fingers of a so-called tulip contact.
The oppositely located contact fingers which are connected at their ends rigidly with a base body of the tulip contact have diverging free end portions, for the insertion of the contact tongs, to facilitate the insertion of the contact tongs between the contact fingers. The oppositely located elastically bendable contact fingers are angled or bent convexly between their free ends and the base body, so that their distance in the region of the apex of the angle or bends is the smallest. At this location the light width (clearance) of an intermediate space for receiving the contact tongs between the both contact fingers is smaller than the corresponding transverse cross-section of the contact tong, or the contact finger located there opposite to it. Thereby the contact surfaces of the contact fingers arranged on the apex are pressed against the corresponding neighboring contact surface of the contact tong, to guarantee a good contact and to fix the contact tong between the oppositely located contact fingers.
In the currently utilized contact arrangements, the apexes of the angles or bends are located exactly opposite to the oppositely located contact fingers. During the use of the contact tongs with a small cross-sectional dimension this results in that, without a utilization of special materials no sufficient clamping forces can be produced when the contact fingers, before the insertion of the contact tongs in the region of the apex, abut against one another without pressure. For increasing the clamping forces, it is however possible to impart a pretensioning to the oppositely located contact fingers, so that in the region of their apex, they are pressed against one another under pressure, when the contact tongs are pulled from the intermediate space between the contact fingers. The contact fingers with a pretensioning provided within a predetermined tolerance field are however more difficult to manufacture. Moreover, it is not possible to guarantee a sufficient clamping force for quality testing by a visual control or another simple measures, since they can not be measured with the pretensioned contact fingers or can be measured only with certain difficulties.